1. Field
The present invention relates to a deep hole processing device like a machine tool for drilling.
2. Related Art
Deep hole processing is making a hole with a large ratio between depth and diameter. In deep hole processing, common processing systems include a gun drill system, a boring and trepanning association (BTA), system and an ejector system.
Deep hole processing tools are typically long and have relatively small diameters relative to their lengths. Therefore, it is difficult to perform of high accuracy processing due to bending and buckling of the tool and rotational deflection of the tool during attachment.
Therefore, conventionally, as illustrated in FIG. 9A, a pilot hole 101 is provided in advance on a workpiece 158 using a short tool and a deep hole is processed using a long tool using the pilot hole as a guide. As illustrated in FIG. 9B, a guide pad 119 provided on an outer periphery of a long tool 108 in a slightly projected manner is brought into contact with the pilot hole 101. Then, as illustrated in FIG. 9C, the processing is performed by a blade 118 provided on a tip end of the tool 108. Alternatively, a bush guide is attached to the processing device and the hole processing is performed using the bush guide as the guide. An example of the conventional deep hole processing device is hereafter described in Japanese Patent Application Laid-Open No. S62-24203
However, when providing the above-described pilot hole, advance processing using the short tool is required, thereby resulting in low work efficiency. Also, when performing the processing using the bush guide, a mechanism to press the bush guide against the workpiece is required and it is problematically difficult to use a general-purpose machine.